Postmortem Brains from Subjects with Diabetes Mellitus Display Reduced GLUT4 Expression and Soma Area in Hippocampal Neurons: Potential Involvement of Inflammation

Caio Yogi Yonamine, Marisa Passarelli, Claudia Kimie Suemoto, Carlos Augusto Pasqualucci, Wilson Jacob-Filho, Venancio Avancini Ferreira Alves, Suely Kazue Nagahashi Marie, Maria Lucia Correa-Giannella, Luiz Roberto Britto, Ubiratan Fabres Machado*

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

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Abstract

Diabetes mellitus (DM) is an important risk factor for dementia, which is a common neurodegenerative disorder. DM is known to activate inflammation, oxidative stress, and advanced glycation end products (AGEs) generation, all capable of inducing neuronal dysfunctions, thus participating in the neurodegeneration progress. In that process, disturbed neuronal glucose supply plays a key role, which in hippocampal neurons is controlled by the insulin-sensitive glucose transporter type 4 (GLUT4). We investigated the expression of GLUT4, nuclear factor NF-kappa B subunit p65 [NFKB (p65)], carboxymethyllysine and synapsin1 (immunohistochemistry), and soma area in human postmortem hippocampal samples from control, obese, and obese+DM subjects (41 subjects). Moreover, in human SH-SY5Y neurons, tumor necrosis factor (TNF) and glycated albumin (GA) effects were investigated in GLUT4, synapsin-1 (SYN1), tyrosine hydroxylase (TH), synaptophysin (SYP) proteins, and respective genes; NFKB binding activity in the SLC2A4 promoter; effects of increased histone acetylation grade by histone deacetylase 3 (HDAC3) inhibition. Hippocampal neurons (CA4 area) of obese+DM subjects displayed reduced GLUT4 expression and neuronal soma area, associated with increased expression of NFKB (p65). Challenges with TNF and GA decreased the SLC2A4/GLUT4 expression in SH-SY5Y neurons. TNF decreased SYN1, TH, and SYP mRNAs and respective proteins, and increased NFKB binding activity in the SLC2A4 promoter. Inhibition of HDAC3 increased the SLC2A4 expression and the total neuronal content of CRE-binding proteins (CREB/ICER), and also counterbalanced the repressor effect of TNF upon these parameters. This study revealed reduced postmortem human hippocampal GLUT4 content and neuronal soma area accompanied by increased proinflammatory activity in the brains of DM subjects. In isolated human neurons, inflammatory activation by TNF reduced not only the SLC2A4/GLUT4 expression but also the expression of some genes related to neuronal function (SYN1, TH, SYP). These effects may be related to epigenetic regulations (H3Kac and H4Kac status) since they can be counterbalanced by inhibiting HDAC3. These results uncover the improvement in GLUT4 expression and/or the inhibition of HDAC3 as promising therapeutic targets to fight DM-related neurodegeneration.

Original languageEnglish
Article number1250
JournalCells
Volume12
Issue number9
Number of pages21
ISSN2073-4409
DOIs
Publication statusPublished - 2023

Keywords

  • GLUT4
  • diabetes
  • obesity
  • human hippocampus
  • SH-SY5Y cell
  • neurodegeneration
  • Alzheimer's disease
  • inflammation
  • histone acetylation
  • HDAC3 inhibition
  • NECROSIS-FACTOR-ALPHA
  • ALZHEIMERS-DISEASE
  • SLC2A4 GENE
  • COGNITIVE IMPAIRMENT
  • GLUCOSE-METABOLISM
  • INSULIN-RESISTANCE
  • 3T3-L1 ADIPOCYTES
  • TNF-ALPHA
  • DEMENTIA
  • ASSOCIATION

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